Cellulase Activity and Fruit Softening in Avocado

Pesis, Edna; Fuchs, Yoram; Zauberman, Giora

doi:10.1104/pp.61.3.416

Cited by 132 publications

(72 citation statements)

References 14 publications

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“…Even during a 9-d period beyond the fully ripe stage, tomato fruit polyuronides exhibited limited additional depolymerization and did not include oligomeric species. A comparison of the data for the avocado and tomato fruit indicates that downshifts in polyuronide molecular weight are a prominent feature of avocado ripening and may also explain why molecular down-regulation of PC (EC 3.2.1.15) in tomato fruit has resulted in minimal effects on fruit performance until the terminal stages of ripening.Avocado fruit soften extensively during ripening, with mesocarp firmness, measured in terms of resistance to penetration, exceeding 450 N at the preripe stage and decreasing severa1 orders of magnitude during ripening (Pesis et al, 1978; Awad and Young, 1979; O'Donoghue and Huber, …”

mentioning

confidence: 99%

Polyuronides in Avocado (Persea americana) and Tomato (Lycopersicon esculentum) Fruits Exhibit Markedly Different Patterns of Molecular Weight Downshifts during Ripening

1993

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Avocado (Persea americana) fruit experience a rapid and extensive loss of firmness during ripening. In this study, we examined whether the chelator solubility and molecular weight of avocado polyuronides paralleled the accumulation of polygalacturonase (PC) activity and loss in fruit firmness. Polyuronides were derived from ethanolic precipitates of avocado mesocarp prepared using a procedure to rapidly inactivate endogenous enzymes. During ripening, chelator (cyclohexane-trans-l,2-diamine tetraacetic acid [CDlA])-soluble polyuronides increased from approximately 30 to 40 pg of galacturonic acid equivalents (mg alcohol-insoluble solids)-' in preripe fruit to 150 to 170 pg mg-' in postclimacteric fruit. In preripe fruit, chelator-extractable polyuronides were of high molecular weight and were partially excluded from Sepharose CL-26-300 gel filtration media. Avocado polyuronides exhibited marked downshifts in molecular weight during ripening. At the postclimacteric stage, nearly all chelator-extractable polyuronides, which constituted from 75 to 90% of total cell wall uronic acid content, eluted near the total volume of the filtration media. Rechromatography of low molecular weight polyuronides on BioCel P-4 disclosed that oligomeric uronic acids are produced in vivo during avocado ripening. l h e gel filtration behavior and pattern of depolymerization of avocado polyuronides were not influenced by the polyuronide extraction protocol (imidazole versus CDTA) or by chromatographic conditions designed to minimize interpolymeric aggregation. Polyuronides from ripening tomato (fycopersicon esculentum) fruit extracted and chromatographed under conditions identical with those used for avocado polyuronides exhibited markedly less rapid and less extensive downshifts in molecular weight during the transition from mature-green to fully ripe. Even during a 9-d period beyond the fully ripe stage, tomato fruit polyuronides exhibited limited additional depolymerization and did not include oligomeric species. A comparison of the data for the avocado and tomato fruit indicates that downshifts in polyuronide molecular weight are a prominent feature of avocado ripening and may also explain why molecular down-regulation of PC (EC 3.2.1.15) in tomato fruit has resulted in minimal effects on fruit performance until the terminal stages of ripening.Avocado fruit soften extensively during ripening, with mesocarp firmness, measured in terms of resistance to penetration, exceeding 450 N at the preripe stage and decreasing severa1 orders of magnitude during ripening (Pesis et al., 1978; Awad and Young, 1979; O'Donoghue and Huber,

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confidence: 99%

Polyuronides in Avocado (Persea americana) and Tomato (Lycopersicon esculentum) Fruits Exhibit Markedly Different Patterns of Molecular Weight Downshifts during Ripening

1993

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“…As a climacteric fruit, avocado ripening is characterized by an increase in the respiration rate accompanied by an increase in ethylene production. Avocado during ripening is characterized by fruit softening [43] due to cell wall dismantling (depolymerization and solubilization) carried out by cellulase, pectin methyl esterase (PME), polugalacturonase (PG), ß-galactosidase, xylanase and xylosidase, enzymes that work in concert or synergistically [44]. In addition, peel color changes in 'Hass' avocados from green to black and synthesis of flavor and aroma compounds take place [2,3].…”

Section: Avocado Fruit Ripening Physiologymentioning

confidence: 99%

Factors associated with postharvest ripening heterogeneity of ‘Hass’ avocados (Persea americanaMill)

Hernández¹,

Fuentealba²,

Olaeta³

et al. 2016

Fruits

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-Introduction. 'Hass' is the main avocado cultivar commercialized worldwide. The extended flowering period, very low percentage of fruit set and inability to ripen on the tree renders the fruit heterogeneous and unpredictable during postharvest management. The "triggered" and "ready-to-eat" growing markets for 'Hass' avocados are affected by the variable postharvest ripening or ripening heterogeneity which creates severe logistical problems for marketers and inconsistent quality delivery to consumers. Synthesis. The dry matter content, the current avocado harvest index that correlates very well with oil content, has been extensively used to harvest 'Hass' avocados to comply with the minimum standards to guarantee consumer satisfaction. However, previous work and empirical experience demonstrate that dry matter does not correlate on a fruit-to-fruit basis with time to reach edible ripeness. Thus, avocados of very different ages are harvested from individual trees, resulting in heterogeneous postharvest ripening of fruit within a specific batch. Several preharvest factors related to environmental and growing conditions and crop management as well as postharvest technology strategies influence the observed variability of postharvest ripening. Conclusion. Modern approaches based on studying the composition of individual fruits displaying contrasting postharvest ripening behavior, combined with non-destructive phenotyping techniques, seem to offer practical solutions for the fresh supply chain of avocados to sort fruit based on their ripening capacity.Keywords: avocado / Persea americana / fruit quality / ripening stage / preharvest management / secondary metabolites / non-destructive analysis Résumé -Facteurs associés à l'hétérogénéité du mûrissement post-récolte des avocats (Persea americana Mill cv. Hass). Introduction. Le 'Hass' est la principale variété d'avocat commercialisée dans le monde. Sa période de floraison prolongée, son très faible pourcentage de nouaison et son incapacité à mûrir sur l'arbre en font un fruit hétéro-gène et imprévisible à gérer après récolte. Le marché croissant des avocats 'Hass' « déclenchés » et « prêts-à-manger » est affecté par la variabilité ou l'hétérogénéité du mûrissement post-récolte, ce qui crée de sérieux problèmes logistiques aux spécialistes du marketing et offre une prestation de qualité inégale aux consommateurs. Synthèse. La teneur en matière sèche, l'actuel indice de récolte des avocats qui correspond parfaitement à la teneur en huile du fruit, a été largement utilisé pour récolter les avocats 'Hass' en conformité avec les normes minimales de garantie de satisfaction des consommateurs. Toutefois, des travaux antérieurs et l'expérience empirique démontrent que la matière sèche ne correspond pas à un paramètre sur lequel se baser d'un fruit à l'autre pour estimer la durée jusqu'au fruit mûr prêt à manger. Ainsi, pour des fruits d'âge très différents récoltés arbre par arbre, il en résulte une hétérogénéité du mûrisse-ment des fruits après récolte dans chaque lo...

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“…These factors affect the appearance, texture, taste, and nutritional value of the fruit; for example, loss of firmness and chilling injury were the main limitations in the retail quality for avocados subjected to fluctuating temperatures (too cold or too warm) during a simulation of the shipping and handling of the fruit. (28).…”

Section: Postharvest Quality Loss and Managementmentioning

confidence: 99%

“…During ripening, a loss of firmness (texture) takes place due to rapid changes that occur in the ultrastructure of the cell wall and its components. (14) These cell wall structural changes are due to the activities of degrading cellulase enzymes in the cell wall (28,33) and polygalacturonase that result in decreased tissue cohesiveness resulting from the degradation of pectin and cell disarrangement. (34) The mesocarp of an avocado contains common heptoses (C7) sugar, mannoheptulose (35) and its corresponding sugar alcohol, perseitol.…”

Section: Fruit Respiration and Ethylene Productionmentioning

confidence: 99%

“…(27) Mature fruit displays a characteristic respiratory pattern that coincides with increased ethylene production. This increase in respiration rate and ethylene biosynthesis is accompanied by a complex of biochemical changes including an increased cellulose activity resulting in fruit softening, (28) flesh color changes and synthesis of flavor and aroma chemicals. (29) The increase in the CO 2 and ethylene (C 2 H 4 ) production rate coincides with ripening, resulting in the amino acid methionine being converted to S-adenosyl methionine, the precursor of 1-aminocyclopropane-1-carboxylic acid, which is the immediate precursor of C 2 H 4 .…”

Section: Fruit Respiration and Ethylene Productionmentioning

confidence: 99%

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Avocado Fruit Quality Management during the Postharvest Supply Chain

Bill¹,

Sivakumar²,

Thompson³

et al. 2014

Food Reviews International

101

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Avocados are a popular subtropical fruit of high economic importance and the European Union is the biggest importer of the bulk of the fruit coming from countries like South Africa, Chile and Israel. The fruit is highly nutritious being rich in vitamins A, B, C, minerals, potassium, phosphorus, magnesium, iron and antioxidants10%. The Guatemalan is native to the Guatemalan highland and has medium round fruit with an oil content of 8 to 15% and a leathery, pliable and non-granular ski n. The tree is less cold tolerant than the Mexican. The Mexican race thrives best in the subtropics and has the smallest fruit of the three races, with a thin skin and the highest oil of up to 30%. (2) The tree is most tolerant of cold growing conditions. Chen et al. (3) confirmed that the substantial genetic differentiation among the three ecological races corresponded to the defined horticultural races, but they also reported that the previously undetected genetic differentiation has two subpopulations from Central Mexico. Many cultivars are hybrids between the races. "Hass" (a Guatemalan x Mexican hybrid) is considered to be the most dominantly grown cultivar in the subtropics (4) and is recognised as the best overall quality avocado available. The fruit weighs between 140 to 400 g with medium to thick skin, leathery, coarse corky in texture and it turns purplish black when ripe. Other popular cultivars include "Fuerte" (a Mexican x Guatemalan hybrid), "Bacon" (a Mexican x Guatemalan hybrid), Pinkerton (a Guatemala hybrid), "Edranol"(a Guatemala hybrid), "Ryan" (a Mexican x Guatemalan hybrid", "Ettinger" (predominantly Mexican) and "Fuchs" (West Indian). (4) The fruit characteristics of the above mentioned cultivars are shown in Table 1. Physical properties of avocadoThe fruit (berry) is pear-shaped, oval or round with a short neck. Fruit length can vary from 7.7 cm to 33 cm and its width can be up to 15 cm. The skin color of the fruit can vary from yellowish green, dark green or reddish-purple, to dark purple (almost black). The edible portion of the fruit, that is, its flesh or pulp can be pale to bright yellow in color and the fruit flavor is described as a buttery or nut-like flavor. Its single seed is situated at the center of the fruit and 3 Table 1 Fruit characteristics of different avocado cultivars a a Source: Whiley et al. (4) the shape of the seed can be oval, round or oblong and generally the length of the seed is around 5 to 6.5 cm long, but may be smaller. The seed is covered by a thin brown seed coat that adheres to the seed cavity. (4) Avocado production and trade European markets. In the EU, the Netherlands and France as well as the UK are the major avocado importing countries. Although the "Fuerte" cultivar displays a green skin color after ripening and is well known in the European markets, the "Hass" cultivar currently dominates the international trade market due to its longer shelf life, large fruit size and its higher consumer acceptance due to its rich nut-like flavor. (11,12) "Hass" is the dominant and m...

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Cellulase Activity and Fruit Softening in Avocado

Cited by 132 publications

References 14 publications

Polyuronides in Avocado (Persea americana) and Tomato (Lycopersicon esculentum) Fruits Exhibit Markedly Different Patterns of Molecular Weight Downshifts during Ripening

Polyuronides in Avocado (Persea americana) and Tomato (Lycopersicon esculentum) Fruits Exhibit Markedly Different Patterns of Molecular Weight Downshifts during Ripening

Factors associated with postharvest ripening heterogeneity of ‘Hass’ avocados (Persea americanaMill)

Avocado Fruit Quality Management during the Postharvest Supply Chain

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